This document provides an overview of antimatter, including its origin, production, properties, and potential uses. In 3 sentences: Antimatter is composed of antiparticles that have the same mass as normal particles but opposite properties like charge. It is produced naturally in high-energy environments like near black holes, and can also be artificially created in particle accelerators. While antimatter could theoretically be used as an ultra-dense fuel source, practical applications are limited by the immense difficulty and costs associated with producing and containing enough antimatter.

1. For other uses, see Antimatter (disambiguation).
Antimatter
Overview
Annihilation
Devices
* Particle accelerator
* Penning trap
Antiparticles
* Positron
* Antiproton
* Antineutron
Uses
* PET
* Fuel
* Weaponry
Bodies
* ALPHA Collaboration
* ATHENA
* ATRAP
* CERN
People
* Paul Dirac
* Carl D. Anderson
* Andrei Sakharov
edit
In particle physics and quantum chemistry, antimatter is the extension of the concept of the
antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal
matter is composed of particles. For example, an antielectron (a positron, an electron with a
positive charge) and an antiproton (a proton with a negative charge) could form an antihydrogen
atom in the same way that an electron and a proton form a normal matter hydrogen atom.
Furthermore, mixing matter and antimatter would lead to the annihilation of both in the same way
that mixing antiparticles and particles does, thus giving rise to high-energy photons (gamma rays)
or other particle–antiparticle pairs.
There is considerable speculation both in science and science fiction as to why the observable
universe is apparently almost entirely matter, whether other places are almost entirely antimatter
instead, and what might be possible if antimatter could be harnessed, but at this time the
apparent asymmetry of matter and antimatter in the visible universe is one of the greatest
unsolved problems in physics. The process of developing particles and antiparticles is called
baryogenesis.
Contents
[hide]
* 1 Notation
* 2 Origin (naturally occurring production)

2. o 2.1 Asymmetry
* 3 Artificial production
o 3.1 Antihydrogen
o 3.2 Antihelium
o 3.3 Preservation
o 3.4 Cost
* 4 Uses
o 4.1 Medical
o 4.2 Fuel
* 5 Antimatter in fiction
o 5.1 Pop culture
o 5.2 Cartoons
o 5.3 Stanisław Lem
* 6 See also
* 7 References
* 8 External links
[edit] Notation
One way to denote an antiparticle is by adding a bar (or macron) over the particle's symbol. For
example, the proton and antiproton are denoted as p and p, respectively. The same rule applies if
you were to address a particle by its constituent components. A proton is made up of u ud quarks,
so an antiproton must therefore be formed from uud antiquarks. Another convention is to
distinguish particles by their electric charge. Thus, the electron and positron are denoted simply
as e− and e+ respectively.
[edit] Origin (naturally occurring production)
[edit] Asymmetry
Most objects observable from the Earth seem to be built of matter rather than antimatter. There is
no current reasoning over why matter prevailed over antimatter, but many believe it was the result
of asymmetry, and some scientists believe that the ratio of this asymmetry was roughly a billion
antimatter particles to a billion and one matter particles[1]. Antiparticles are created everywhere in
the universe where high-energy particle collisions take place. High-energy cosmic rays impacting
Earth's atmosphere (or any other matter in the solar system) produce minute quantities of
antimatter in the resulting particle jets, which are immediately annihilated by contact with nearby
matter. It may similarly be produced in regions like the center of the Milky Way Galaxy and other
galaxies, where very energetic celestial events occur (principally the interaction of relativistic jets
with the interstellar medium). The presence of the resulting antimatter is detectable by the
gamma rays produced when positrons annihilate with nearby matter. The gamma rays' frequency
and wavelength indicate that each carries 511 keV of energy (i.e. the rest mass of an electron or
positron multiplied by c2). Recent observations by the European Space Agency’s INTEGRAL
(International Gamma-Ray Astrophysics Laboratory) satellite may explain the origin of a giant
cloud of antimatter surrounding the galactic center. The observations show that the cloud is
asymmetrical and matches the pattern of X-ray binaries, binary star systems containing black
holes or neutron stars, mostly on one side of the galactic center. While the mechanism is not fully
understood, it is likely to involve the production of electron-positron pairs, as ordinary matter
gains tremendous energy while falling into a stellar remnant.[2][3]
[edit] Artificial production
Antiparticles are also produced in any environment with a sufficiently high temperature (mean
particle energy greater than the pair production threshold). During the period of baryogenesis,
when the universe was extremely hot and dense, matter and antimatter were continually
produced and annihilated. The presence of remaining matter, and absence of detectable

3. remaining antimatter,[4] also called baryon asymmetry, is attributed to violation of the CP-
symmetry relating matter and antimatter. The exact mechanism of this violation during
baryogenesis remains a mystery.
Positrons are also produced via the radioactive beta+ decay, but this mechanism can be
considered as "natural" as well as "artificial".
[edit] Antihydrogen
In 1995 CERN announced that it had successfully created nine antihydrogen atoms by
implementing the SLAC/Fermilab concept during the PS210 experiment. The experiment was
performed using the Low Energy Antiproton Ring (LEAR), and was led by Walter Oelert and
Mario Macri. Fermilab soon confirmed the CERN findings by producing approximately 100
antihydrogen atoms at their facilities.
The antihydrogen atoms created during PS210, and subsequent experiments (at both CERN and
Fermilab) were extremely energetic ("hot") and were not well suited to study. To resolve this
hurdle, and to gain a better understanding of antihydrogen, two collaborations were formed in the
late 1990s — ATHENA and ATRAP. In 2005, ATHENA disbanded and some of the former
members (along with others) formed the ALPHA Collaboration, which is also situated at CERN.
The primary goal of these collaborations is the creation of less energetic ("cold") antihydrogen,
better suited to study.
In 1999 CERN activated the Antiproton Decelerator, a device capable of decelerating antiprotons
from 3.5 GeV to 5.3 MeV — still too "hot" to produce study-effective antihydrogen, but a huge
leap forward. In late 2002 the ATHENA project announced that they had created the world's first
"cold" antihydrogen. The antiprotons used in the experiment were cooled sufficiently by
decelerating them (using the Antiproton Decelerator), passing them through a thin sheet of foil,
and finally capturing them in a Penning trap. The antiprotons also underwent stochastic cooling at
several stages during the process.
The ATHENA team's antiproton cooling process is effective, but highly inefficient. Approximately
25 million antiprotons leave the Antiproton Decelerator; roughly 10 thousand make it to the
Penning trap. In early 2004 ATHENA researchers released data on a new method of creating
low-energy antihydrogen. The technique involves slowing antiprotons using the Antiproton
Decelerator, and injecting them into a Penning trap (specifically a Penning-Malmberg trap[citation
needed]). Once trapped the antiprotons are mixed with electrons that have been cooled to an
energy potential significantly less than the antiprotons; the resulting Coulomb collisions cool the
antiprotons while warming the electrons until the particles reach an equilibrium of approximately 4
K.
While the antiprotons are being cooled in the first trap, a small cloud of positron plasma is
injected into a second trap (the mixing trap). Exciting the resonance of the mixing trap’s
confinement fields can control the temperature of the positron plasma; but the procedure is more
effective when the plasma is in thermal equilibrium with the trap’s environment. The positron
plasma cloud is generated in a positron accumulator prior to injection; the source of the positrons
is usually radioactive sodium.
Once the antiprotons are sufficiently cooled, the antiproton-electron mixture is transferred into the
mixing trap (containing the positrons). The electrons are subsequently removed by a series of fast
pulses in the mixing trap's electrical field. When the antiprotons reach the positron plasma further
Coulomb collisions occur, resulting in further cooling of the antiprotons. When the positrons and
antiprotons approach thermal equilibrium antihydrogen atoms begin to form. Being electrically
neutral the antihydrogen atoms are not affected by the trap and can leave the confinement fields.
Using this method ATHENA researchers predict they will be able to create up to 100

4. antihydrogen atoms per operational second. ATHENA and ATRAP are now seeking to further
cool the antihydrogen atoms by subjecting them to an inhomogeneous field. While antihydrogen
atoms are electrically neutral, their spin produces magnetic moments. These magnetic moments
vary depending on the spin direction of the atom, and can be deflected by inhomogeneous fields
regardless of electrical charge.
The biggest limiting factor in the production of antimatter is the availability of antiprotons. Recent
data released by CERN states that when fully operational their facilities are capable of producing
107 antiprotons per second.[citation needed] Assuming an optimal conversion of antiprotons to
antihydrogen, it would take two billion years to produce 1 gram of antihydrogen (approximately
6.02×1023 atoms of antihydrogen.) Another limiting factor to antimatter production is storage. As
stated above there is no known way to effectively store antihydrogen. The ATHENA project has
managed to keep antihydrogen atoms from annihilation for tens of seconds — just enough time to
briefly study their behaviour.
Hydrogen atoms are the simplest objects that can be considered as "matter" rather than as just
particles. Simultaneous trapping of antiprotons and antielectrons was reported[5] and the cooling
is achieved;[6] there are patents on the way of production of antihydrogen.[7]
[edit] Antihelium
A small number of nuclei of the antihelium isotope, overline{mathrm{^3He}} have been created
in collision experiments.[8]
[edit] Preservation
Antimatter cannot be stored in a container made of ordinary matter because antimatter reacts
with any matter it touches, annihilating itself and the container. Antimatter that is composed of
charged particles can be contained by a combination of an electric field and a magnetic field in a
device known as a Penning trap. This device cannot, however, contain antimatter that consists of
uncharged particles, and atomic traps are used. In particular, such a trap may use the dipole
moment (electrical or magnetic) of the trapped particles; at high vacuum, the matter or anti-matter
particles can be trapped (suspended) and cooled with slightly off-resonant laser radiation (see,
for, example, magneto-optical trap and Magnetic trap). Small particles can be also suspended by
just intensive optical beam in the optical tweezers.
[edit] Cost
Antimatter is said to be the most expensive substance in existence, with an estimated cost of
$300 billion per milligram.[9] This is because production is difficult (only a few atoms are
produced in reactions in particle accelerators), and because there is higher demand for the other
uses of particle accelerators. According to CERN, it has cost a few hundred million Swiss Francs
to produce about 1 billionth of a gram.[10]
Several NASA Institute for Advanced Concepts-funded studies are exploring whether it might be
possible to use magnetic scoops to collect the antimatter that occurs naturally in the Van Allen
belts of Earth, and ultimately, the belts of gas giants like Jupiter, hopefully at a lower cost per
gram.[11]
[edit] Uses
[edit] Medical
Antimatter-matter reactions have practical applications in medical imaging, such as positron
emission tomography (PET). In positive beta decay, a nuclide loses surplus positive charge by
emitting a positron (in the same event, a proton becomes a neutron, and neutrinos are also given

5. off). Nuclides with surplus positive charge are easily made in a cyclotron and are widely
generated for medical use.
[edit] Fuel
In antimatter-matter collisions resulting in photon emission, the entire rest mass of the particles is
converted to kinetic energy. The energy per unit mass (9×1016 J/kg) is about 10 orders of
magnitude greater than chemical energy (compared to TNT at 4.2×106 J/kg, and formation of
water at 1.56×107 J/kg), about 4 orders of magnitude greater than nuclear energy that can be
liberated today using nuclear fission (about 40 MeV per 238U nucleus transmuted to Lead, or
1.5×1013 J/kg), and about 2 orders of magnitude greater than the best possible from fusion
(about 6.3×1014 J/kg for the proton-proton chain). The reaction of 1 kg of antimatter with 1 kg of
matter would produce 1.8×1017 J (180 petajoules) of energy (by the mass-energy equivalence
formula E = mc²), or the rough equivalent of 47 megatons of TNT. For comparison, Tsar Bomba,
the largest nuclear weapon ever detonated, reacted an estimated yield of 57 Megatons, which
required the use of hundreds of kilograms of fissile material (Uranium/Plutonium).
Not all of that energy can be utilized by any realistic technology, because as much as 50% of
energy produced in reactions between nucleons and antinucleons is carried away by neutrinos,
so, for all intents and purposes, it can be considered lost.[12]
The scarcity of antimatter means that it is not readily available to be used as fuel, although it
could be used in antimatter catalyzed nuclear pulse propulsion. Generating a single antiproton is
immensely difficult and requires particle accelerators and vast amounts of energy—millions of
times more than is released after it is annihilated with ordinary matter due to inefficiencies in the
process. Known methods of producing antimatter from energy also produce an equal amount of
normal matter, so the theoretical limit is that half of the input energy is converted to antimatter.
Counterbalancing this, when antimatter annihilates with ordinary matter, energy equal to twice the
mass of the antimatter is liberated—so energy storage in the form of antimatter could (in theory)
be 100% efficient.
Antimatter production is currently very limited, but has been growing at a nearly geometric rate
since the discovery of the first antiproton in 1955 by Segrè and Chamberlain.[citation needed]
The current antimatter production rate is between 1 and 10 nanograms per year, and this is
expected to increase to between 3 and 30 nanograms per year by 2015 or 2020 with new
superconducting linear accelerator facilities at CERN and Fermilab. Some researchers claim that
with current technology, it is possible to obtain antimatter for US$25 million per gram by
optimizing the collision and collection parameters (given current electricity generation costs).
Antimatter production costs, in mass production, are almost linearly tied in with electricity costs,
so economical pure-antimatter thrust applications are unlikely to come online without the advent
of such technologies as deuterium-tritium fusion power (assuming that such a power source
actually would prove to be cheap). Many experts, however, dispute these claims as being far too
optimistic by many orders of magnitude. They point out that in 2004; the annual production of
antiprotons at CERN was several picograms at a cost of $20 million. This means to produce 1
gram of antimatter, CERN would need to spend 100 quadrillion dollars and run the antimatter
factory for 100 billion years. Storage is another problem, as antiprotons are negatively charged
and repel against each other, so that they cannot be concentrated in a small volume. Plasma
oscillations in the charged cloud of antiprotons can cause instabilities that drive antiprotons out of
the storage trap. For these reasons, to date only a few million antiprotons have been stored
simultaneously in a magnetic trap, which corresponds to much less than a femtogram.
Antihydrogen atoms or molecules are neutral so in principle they do not suffer the plasma
problems of antiprotons described above. But cold antihydrogen is far more difficult to produce
than antiprotons, and so far not a single antihydrogen atom has been trapped in a magnetic field.
Since the energy density is vastly higher than these other forms, the thrust to weight equation
used in antimatter rocketry and spacecraft would be very different. In fact, the energy in a few

6. grams of antimatter is enough to transport an unmanned spacecraft to Mars in a few minutes. In
comparison, the Mars Global Surveyor took eleven months to reach Mars using conventional
means. It is hoped that antimatter could be used as fuel for interplanetary travel or possibly
interstellar travel, but it is also feared that, as a side-effect of antimatter propulsion, the design of
antimatter weapons might become an equal reality.
One researcher of the CERN laboratories, which produces antimatter regularly, said:
“ If we could assemble all of the antimatter we've ever made at CERN and annihilate it with
matter, we would have enough energy to light a single electric light bulb for a few minutes.[13]
”
[edit] Antimatter in fiction
Lists of miscellaneous information should be avoided. Please relocate any relevant
information into appropriate sections or articles. (June 2008)
Existence of anti-particles is more "science" than "fiction" .[14] However, until now, the anti-world,
or even macroscopic amounts of antimatter exist rather in jokes and science-fiction novels, than
in laboratories.
[edit] Pop culture
The 1960s hit television show The Man from U.N.C.L.E. dealt with the potential of antimatter in an
episode called The Suburbia Affair. Pianist and comedian Victor Borge played a pianist and
scientist who had come up with a formula for antimatter and, fearing its destructive potential, hid
in a bizarre suburban development populated by single adults and couples who hate children.
Borge's character, Dr. Rutter, disguised his formula in a dissonant piece of music until forced to
reveal it to the evil organization, THRUSH (Technological Hierarchy for the Removal of
Undesirables and Subjugation of Humanity). The good guys, Illya Kuryakin and Napoleon Solo,
arrive to save the day and, after a plea from the wounded Rutter, destroy the computer where the
antimatter formula has been stored. In another 20 years, Rutter warns, someone else will come
up with the formula.
In the television series Star Trek, the Enterprise (starship) was equipped with a faster-than-light
drive called a "Warp Drive", which harnessed the energy released by matter-antimatter
annihilation to propel the vessel at superluminary velocity, as well as weapons called "Photon
Torpedoes", which contained a charge of antimatter contained in an unspecified manner, and
could be fired at enemy vessels much like missiles from a present day fighter plane.
An antimatter particle colliding with a matter particle releases 100% of the energy contained
within the particles, while a hydrogen bomb only releases about 0.7% of this energy. Because of
this potential to release immense amounts of energy in contact with normal matter, antimatter
weapons are popular in science fiction stories and games, such as in Peter F. Hamilton's Night's
Dawn Trilogy , Sega and Petroglyph Games's RTS game Universe at War, Dan Brown's Angels
and Demons and Spore.
[edit] Cartoons
In the Dilbert cartoon strip from June 30, 2008, Dilbert creates an "anti-Dilbert" using a particle
accelerator.[15]
[edit] Stanisław Lem
Stanisław Lem
Stanisław Lem
In the novel The Cyberiad, Stanisław Lem describes the building up the antimatter in the following
way:[16]

7. * The machine, however, had already begun. First it manufactured antiprotons, then
antielectrons, antineutrons, antineutrinos, and labored on, until from out of all this antimatter an
antiworld took shape, ..
In another novel, The Invincible ,[17] the researchers fail to fight the self-organizing microrobots,
even though they use antimatter as a weapon.
In the novel Eden ,[18] humans use antimatter as a weapon, but it does not help them to
understand anything about the civilization they met.